Thin polished plates such as silicon wafers and the like are a very important part of modern technology. A wafer, for instance, may refer to a thin slice of semiconductor material used in the fabrication of integrated circuits and other devices. Other examples of thin polished plates may include magnetic disc substrates, gauge blocks and the like. While the technique described here refers mainly to wafers, it is to be understood that the technique also is applicable to other types of polished plates as well. The term wafer and the term thin polished plate may be used interchangeably in the present disclosure.
Wafers are subjects to defect inspections. Tools utilized to perform such inspections are expected to be efficient and effective. It is noted, however, that recent developments in large scale circuit integration and size reduction have challenged that expectation. That is, existing inspection tools are becoming less efficient and effective in detecting defects as that defects are becoming increasingly smaller.
Therein lies a need for improved inspection systems without the aforementioned shortcomings.